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排序方式: 共有659条查询结果,搜索用时 15 毫秒
11.
M Lopez de Ceballos E Guisado P Sanchez-Blazquez J Garzon J Del Rio 《Neuroscience letters》1983,39(2):217-222
Rats isolated at the time of calcification of the incisors show, after 14-18 months of social deprivation, an increased number of alpha 1-adrenoceptors labeled with [3H]WB 4101, both in the striatum and in the vas deferens, as well as a decreased number of alpha 2-adrenoceptors labeled with [3H]-clonidine in the vas deferens. Social isolation does not, however, modify the density of [3H]clonidine binding sites in the cerebral cortex. The functional state of alpha-adrenoreceptors in the vas deferens from isolated rats appears to correlate with the binding studies since the isolated tissue is hypersensitive to the contractile effect of exogenous noradrenaline and subsensitive to the inhibitory effect of clonidine on the electrically stimulated preparation. 相似文献
12.
Temporal relationship between noradrenaline release in the central amygdala and plasma noradrenaline secretion in rats and tree shrews 总被引:1,自引:0,他引:1
H Dietl 《Neuroscience letters》1985,55(1):41-46
In pentobarbital anesthetized Wistar rats and tree shrews (Tupaia belangeri) the hypothalamus, the hippocampus and the amygdala were simultaneously superfused through push-pull cannulae with artificial cerebrospinal fluid. Blood samples were withdrawn in order to make an attempt to correlate release rates of noradrenaline (NA), adrenaline and dopamine in the above-mentioned areas with plasma catecholamine levels. A strong, positive correlation was found between NA release in central amygdala and NA concentrations in peripheral blood suggesting a functional relationship between noradrenergic systems in discrete brain areas and the activity of the peripheral sympathetic nervous system. 相似文献
13.
Summary Guinea pig vas deferens was used as an animal model for alpha-1 adrenoceptor (1-receptor) mediated contractions in human hyperplastic prostatic tissue. The selective 1-receptor agonist, phenylephrine (PE), induced fully reversible, dose-dependent contractions antagonized by increasing concentrations of the 1-receptor blockers prazosin (1–100 nM) and YM 617 (0.1–10 nM). Removal of extracellular Ca2+ reduced PE-evoked contractions in a time-dependent manner. Nifedipine (1–1000 nM), a blocker of voltage-dependent L-type Ca2+ channels (VDCC), inhibited the PE-induced response by up to 65%. Removal of extracellular Ca2+ abolished the 1-agonist reactivity in a time-dependent fashion. To elucidate the participation of intracellular Ca2+ stores in 1-receptor contractions, the tissue was pretreated with ryanodine (10 M) or thapsigargin (0.1 M), established inhibitors of Ca2+ release from intracellular pools. Both substances reduced the PE contractions by up to 80%. Nifedipine suppressed the remaining contractions completely. This provides evidence that Ca2+ influx through VDCC and Ca2+ release from intracellular stores contribute to 1-receptor contractions in the guinea pig vas deferens and may be important in obstructive benign prostatic hyperplasia. 相似文献
14.
Ralph Bültmann Bernd Driessen Jorge Gonçalves Klaus Starke 《Naunyn-Schmiedeberg's archives of pharmacology》1995,351(5):555-560
The effect of Evans blue on nucleotide breakdown, nucleotide-evoked contractions and electrically evoked contractions, overflow of ATP and overflow of tritium (after labelling with [3H]-noradrenaline) was studied in rat vas deferens. Pieces of vas deferens degraded 83 to 85% of added ATP, ADP and 2-methylthio ATP (all 100 M) over 30 min. Evans blue (100 M) reduced this degradation to 22 to 26%. Nucleotides elicited contraction with potency declining in the order , \-methylene ATP > 2-methylthio ATP > ATP > ADP. Evans blue (100 M) shifted the concentration-response curve of , \-methylene ATP to the right and increased the maximum. Concentration-response curves of ATP, ADP and 2-methylthio ATP, in contrast, were shifted to the left and responses were much potentiated. In the presence of Evans blue, the rank order of potency was ATP > 2-methylthio ATP > , \-methylene ATP > ADP. Electrical field stimulation (100 pulses at 10 Hz) elicited contraction and an overflow of tritium and ATP. Evans blue (100 M) did not alter the contraction and the evoked overflow of tritium but increased 24-fold the evoked overflow of ATP. The results indicate that Evans blue may serve as an — albeit impure — ecto-nucleotidase inhibitor in functional experiments. Such experiments demonstrate that the low potency of ATP (and also ADP and 2-methylthio ATP) in eliciting contraction, and the small size of the overflow of ATP upon sympathetic nerve stimulation, are due to rapid breakdown. 相似文献
15.
D. J. Trezise A. D. Michel C. B. A. Grahames B. S. Khakh A. Surprenant P. P. A. Humphrey 《Naunyn-Schmiedeberg's archives of pharmacology》1995,351(6):603-609
The effects of the putative selective P2X purinoceptor agonist, ,-methylene-l-adenosine 5-triphosphate (me-l-ATP), were determined at rat neuronal and smooth muscle P2X purinoceptors.Me-l-ATP had no effect on the extracellularly recorded membrane potential of the rat isolated vagus nerve preparation at concentrations up to 300 M. In contrast, the archetypal P2X purinoceptor agonist, , methylene ATP (meATP;1–100 M), produced concentration-related depolarisation responses with a mean EC50 value of 10.8 M. The depolarising effects of meATP were not attenuated by me-l-ATP (100 M). In voltage clamp experiments on single nodose ganglion neurones, ATP (100 M), but not me-l.-ATP (1–300 M), evoked rapid ( < 20 ms onset) inward currents when applied using a concentration-clamp method. In receptor binding studies to rat brain membranes, me-d-ATP and meATP competed with high affinity for [3H]Lx meATP binding sites, with mean pIC50 values of 7.7 and 8.3, respectively. However, me-l-ATP possessed low affinity for these sites and competed only at concentrations in excess of 10 M (mean pIC50 value 4.1).In prostatic segments of the rat vas deferens, me-l-ATP (1–100 M) and meATP (0.3–100 M) each produced concentration-related contractile responses with mean EC50 values of 17.1 and 3.6 M, respectively. Me-l-ATP (1–10 M) evoked fast inward currents in freshly dispersed vas deferens smooth muscle cells, indicative of an action at ligand-gated ion channels. Binding sites in vas deferens membranes labelled using 1 nM [3H]meATP exhibited high affinity for me-l-ATP, meATP and me-d-ATP with mean PIC50 values of 7.7, 8.4 and 7.3, respectively.These results indicate that me-l-ATP exhibits neither agonist nor antagonist properties at P2X purinoceptors on rat vagal neurones and possesses only very low affinity for [3H]meATP binding sites in rat brain. In contrast, me-l-ATP is a potent, high affinity agonist at smooth muscle P2X purinoceptors of the rat vas deferens. This selective agonist action of me-l-ATP suggests that P2X purinoceptors in smooth muscle and neurones are different and represent distinct P2X purinoceptor subtypes. 相似文献
16.
目的 探讨输精管切断精索鞘膜分隔术的效果,总结男性绝育手术经验。方法 对240例输精管切断精索鞘膜分隔术和同期施行的242 例输精管结扎术随访,进行比较和分析总结。结果 两组术后结节发生率有明显差异( P< 001) ,感染率有极显著差异( P< 005) ,腰痛发生率也有明显差异( P< 001) ,均达到绝育目的。结论 输精管切断精索鞘膜分隔术后无痛性结节,腰痛发生率极低,是男性绝育手术的好方法。 相似文献
17.
R. Bültmann Marie Trendelenburg Florin Tuluc Henning Wittenburg Klaus Starke 《Naunyn-Schmiedeberg's archives of pharmacology》1999,359(4):339-344
In order to assess the consequences of a concomitant blockade of P2X-receptors and ecto-nucleotidases, effects of 13 P2-receptor
antagonists were investigated on contractions of the rat vas deferens elicited by α,β-methylene ATP (α,β-MeATP) and ATP and
on the removal of ATP from the incubation medium by vas deferens tissue.
Increasing concentrations of all antagonists reduced and finally abolished contractions elicited by α,β-MeATP (3 μM), with
IC50-values ranging from 1.1 to 100 μM. Pyridoxalphosphate-6-azophenyl-2’,4’-disulphonate (PPADS), 6-azophenyl-4-amino-5-hydroxy-naphthalene-1,3-disulphonate
(NH02), 4,4’-diisothiocyanatostilbene-2,2’-disulphonate (DIDS) and uniblue A also progressively reduced and finally abolished
contractions elicited by ATP (1 mM). 8,8’-[Carbonylbis(imino-3,1-phenylenecarbonyl-imino)]-bis-(1,3,5-naphthalenetrisulphonate)
(NF023), sura- min, pyridoxalphosphate-6-azophenyl-2’,5’-disulphonate (iso-PPADS), trypan blue and reactive blue 19, in contrast,
caused only partial blockade, by 34–43% maximally; reactive blue 2 and reactive red 2 had no effect; and 6,6’-(1,1’-biphenyl-4,4’-diylbisazo)-bis-4-amino-5-hydroxy-naphtha-lene-1,3-disulphonate
(NH01) and Evans blue even enhan- ced the response to ATP. For antagonists causing full or partial inhibition, the IC50-values against ATP were close to those against α,β-MeATP. All antagonists attenuated the removal of ATP, with IC25%-values ranging from 0.8 μM to >320 μM.
The results confirm the frequent combination, in one antagonist molecule, of P2-receptor blockade and blockade of ecto-nucleotidases.
This dual action underlies the effect of such compounds on contractions of the vas deferens elicited by ATP which, for certain
substances (e.g., suramin, reactive blue 2), can be explained by a simple model in which the antagonist simultaneously blocks
the degradation of ATP and a single contraction-mediating receptor (P2X1). Several observations, however, do not conform with this model, and the existence of multiple contraction-mediating receptors
for ATP or multiple, pharmacologically distinct ecto-nucleotidases has to be considered.
Received: 23 October 1998 / Accepted: 11 January 1999 相似文献
18.
对于高位隐睾不能Ⅰ期手术降入阴囊者采用了“长袢输精管”固定术,共治疗12例17侧隐睾,16侧效果满意。随访中对睾丸部位、大小、弹性作了估价。认为手术成功的关键在于高位切断精索、保留输精管血管及睾丸引带侧支。 相似文献
19.
The venom of R. oxyrhynchus, a member of the psammophiine subfamily of the colubrid assemblage, was examined for biological activity using biochemical and pharmacological techniques. Venom displayed a high protein content, a complex electrophorectic profile and PLA2 activity but no detectable proteolytic or haematological activities. In the chick biventer cervicis nerve muscle preparation, venom (1-10 microg/ml) displayed postsynaptic neurotoxic activity as evidenced by inhibition of indirect (0.1 Hz, 0.2 ms, supramaximal V) twitches and responses to exogenous acetylcholine (1 mM) and carbachol (20 microM). This inhibitory effect was poorly reversible by washing. Venom (30-50 microg/ml) caused a rapid and readily reversible inhibition of direct (0.1 Hz, 2 ms, supramaximal V) twitches of the chick biventer cervicis nerve muscle preparation without morphological changes to the muscle fibers. Venom (30-100 microg/ml) inhibited electrically-evoked (0.2 Hz, 0.3 ms, 70-100 V) twitches of the prostatic segment of the rat vas deferens. This inhibitory effect was not significantly attenuated by 8-phenyltheophylline (8-PT; 20 microM), idazoxan (1 microM), a combination of ranitidine (0.2 microM) and thioperamide (10 microM) or capsazepine (10 microM). Venom (5 mg/kg) induced hypotension with subsequent cardiovascular collapse in the anaesthetised rat. The cardiovascular collapse was prevented by artificial respiration of the animals prior to venom administration. The biological activities demonstrated by R. oxyrhynchus venom may aid in prey envenomation strategies such as prey immobilisation. This study provides further evidence that colubrid venoms are comprised of multiple components which can display a variety of actions, some of which may be novel, therefore reinforcing the largely untapped potential of colubrid venoms. 相似文献
20.